It is quite common for a commercial excavator to dig a series of spaced holes for receiving a number of respective elongated objects, such as utility poles. The excavation of the holes may take place before the utility poles can be located into the holes and therefore the holes may be left in a condition to receive the poles for a day or more. Because this is not safe, the holes are usually covered over by any convenient cover such as a board or pallet and the public danger may be signaled by a warning pylon placed over the board.
An improvement over such an improvised safety cover is to provide a tubular insert sized to fit the diameter of the hole and to place the insert into the hole. A protective cap having an internal diameter which is sized to fit over the external diameter of the insert is used to seal off the hole. The insert has the advantage of retaining surrounding soil and dirt so that it does not collapse into the hole thereby preserving the hole so that it can receive a utility pole at a later time.
The insert is usually provided in lengths which are commensurate with the depth of the hole and may vary in lengths of several feet to ten feet or more. One problem which arises with such inserts is that they are preferably withdrawn from the surrounding hole in order to be reused at another job site. With deep holes, this becomes particularly difficult because the entire length of the insert must be withdrawn and if this is done after the utility pole has been installed, the tubular insert must be lifted the entire height of the utility pole as well. Another problem which arises is that the smooth tubular surface of the insert is difficult to grasp for removal. In addition, the diameter of such tubes must in some cases be quite large and storage for transportation takes up a lot of space.
U.S. Pat. No. 7,966,772 and Canadian Patent No. 2,547,084 teach a tubular insert sleeve system for an excavated hole in which the sleeve is made of cooperating segments which can easily be separated and which form a sleeve when assembled. In a preferred embodiment, the sleeve is made of two cooperating segments, each segment extending the full height of the sleeve so that the joint between segments extends longitudinally along the height of the assembled sleeve. The operatively upper end of the assembled sleeve has an outwardly extending portion of greater outer diameter than the outer diameter of the remainder of the sleeve. The upper end thereby defines an outwardly extending flange which is more easily grasped for removal of the sleeve from an excavated hole and which in use will rest on the ground to surround the excavated hole.
The tubular insert sleeve system taught by U.S. Pat. No. 7,966,772 and Canadian Patent No. 2,547,084 include a snug fitting and removable safety cover adapted to extend over the upper end of the tubular insert sleeve in order to cover the excavated hole. However, there remains a risk that a curious or mischievous school age child or adolescent could remove the cover and then climb or fall into the hole and become trapped therein.